The incorporation of electronic devices with pneumatic tire structures yields many practical advantages. Tire electronics may include sensors and other components for obtaining information regarding various physical parameters of a tire, such as temperature, pressure, number of tire revolutions, vehicle speed, etc. Such performance information may become useful in tire monitoring and warning systems, and may have potential use as a part of a feedback system to regulate or control certain tire and/or vehicle related systems. Yet another potential capability offered by electronics systems integrated with tire structures corresponds to asset tracking and performance characterization for commercial vehicular applications.
Sensors using piezoelectric-based technology have been used in various tire embodiments for a variety of purposes. For example, piezoelectric elements have been used to generate power within a tire. Piezoelectric sensors have been used to function as a revolution counter within a tire. Piezoelectric sensors have even been used to determine deflection, load, acceleration and other parameters.
One important parameter of interest related to tire performance is the tire force variation, a tire property that characterizes the dynamic behavior of the forces it experiences in radial, lateral or fore-aft directions. Radial force variation is often of primary interest in tire analysis as it provides a quantifiable indication of tire uniformity. Both high speed and low speed tire uniformity indicators have proven useful in characterizing the performance and ride comfort afforded by particular tires. As such, it may be desirable to monitor tire force variation levels associated with a tire to make sure that a tire does not exceed desired threshold limits or other defined standards for a tire. In addition, tire force variation levels may be monitored to determine other features related to tire uniformity, including but not limited to tire stiffness, thickness variation, radial run out and other geometric tire parameters.
Although many piezo-based tire sensors have been employed, a need remains for a robust and reliable piezo-based system and method for determining tire uniformity parameters such as tire force variation and others from piezoelectric measurements in the tire counter-deflection zone. No known design has emerged that generally encompasses all of the desired characteristics as hereafter presented in accordance with the subject technology.